For some reason, Apple only allows one line in iChat's message composition field. You can change this with a free module designed for Unsanity's free Application Enhancer system called iChat Enhancer. After installing, you can choose how many text lines you wish to use in iChat...

I can't get this to work for me.......
Authored by: Connie on Oct 07, '02 10:12:31AM

I can't get it to work either. I've done everything you all have said. No luck. When trying to get an application to open it all are grayed out or the ones that aren't give me a message of error type -10814. I've done everything I can think of. Just won't do anything.
Connie
Cube running Jaguar

I never understood why people want so many input lines in an IM app. I find it annoying when someone "instant" messages me a friggin novel, or spends 5 minutes writing a reply in an IM window. Its INSTANT. If you need a few hundred words, send an email.

It appears that if you're running iChat Enhancer under Mac OS X 10.2.1 and didn't run it under 10.2, you will need to do the following to change the number of lines displayed (note the different case from what I posted above):

Just mentioning that if you have iChat AV, you can remove the "iChatEnhancer" directory from "/Library/Application Enhancers" or wherever it is. (If you don't, and you have it, you'll get 3 new lines instead of one whenever you type on to the next line.)